Remotely operated submerged dredging system

ABSTRACT

A remotely operated underwater dredging system that can excavate many hundreds of feet below the surface of a water body. By placing dredge pump at the bottom of the water body, the vacuum to lift water and dredged material to the pump is minimized. In addition, the mechanical advantage of the cutterhead can be greatly enhanced by mounting it directly to a submerged dredging chassis close to the pump.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 USC §119(e) of U.S.Provisional Application No. 61/195,398, filed on Oct. 7, 2008 and U.S.Provisional Application No. 61/275,207, filed on Aug. 27, 2009.

BACKGROUND OF THE INVENTION

Hydraulic cutterhead dredges customarily are mounted on barges floatingon water surfaces. The suction pipe and cutterhead are mounted on agirder called a ladder that swings downward to the water bottom from apivotal mounting on the barge. The depth of excavation is limited by twofactors. The lack of mechanical advantage of the cutterhead as it getsmuch deeper than 45 feet, and by cavitation at the pump caused by thevacuum to lift water and dredged materials, being below the vaporpressure of water at the surface.

SUMMARY OF THE INVENTION

By placing dredge pump at the bottom of the water body, the vacuum tolift water and dredged material to the pump is minimized. In addition,the mechanical advantage of the cutterhead can be greatly enhanced bymounting it directly to a submerged dredging chassis close to the pump.The present invention comprises, in addition to accessory apparatusspecialized for submerged remote control, two related apparatuses:

Embodiment 1

An elegant chassis with a means to traverse the cutterhead and pumpwith, for instance, a rack and pinion, jack screw, or endless cablewayin a path on a track along the chassis of the dredge. This embodimentalso provides a hydraulic means to move the dredge position in anydirection on the bottom to further the excavation. The dredge is heldstationary, by utilizing multiple spuds just as utilized commonly onfloating excavators. The chassis in this embodiment also provideshydraulic rams to crowd the track with traversing cutterhead and suctionapart from the chassis and toward the workface.

Embodiment 2

The cutterhead and pump are swung in a curved path along the workface byattaching one end of a long beam or spar to the cutterhead and pump andattaching a large pointed plow to the other end. The spar pivoting onthe buried plow at one end determines an arc that establishes thecurvature radius of the path of the cutter and pump at the other end.Embodiment 2 carries the cutter end of the radius spar with large(optionally driven) wheels rolling in a curved path on the bottom of theexcavation to facilitate swinging the cutter in an arc determined by thespar on its pivot. Cables anchored right and left and spooled on winchesat the cutter end of the spar help swing the spar end right and left. Aslight variation places the wheels supporting the spar on a curved metaltrack on the bottom of the excavation and allows for the use of a rackand pinion or endless cableway on the curved track to traverse thecutter and spar. The configuration of the cutter and pump is detailed inthe descriptions of the embodiments with reference to the drawings.

Both embodiments rely on an ROV, its umbilical attached to the dredgeumbilical to supply power, electronic control data, and compressed airto provide lightening buoyancy to reposition anchors and to performother tasks on the bottom. Both embodiments should be about equallyproductive.

OBJECTS AND ADVANTAGES OF THE INVENTION

Objects and advantages of the invention are:

A closely coupled cutterhead pump assembly is at a great advantagedredging hard or rocky material. A remotely operated submerged dredgeapparatus, can work far below the surface, hundreds, even thousands offeet. Other excavation methods, like open pit mining or hard rockunderground mining, have a much larger footprint on a vulnerableenvironment and are far more expensive. An application for such a dredgein an environmentally sensitive region is diamond mining in NorthernCanada. A kimberlite pipe containing diamonds is typically a narrowcarrot shaped volcanic intrusion. If possible, the present inventionwould excavate only that narrow carrot shape eliminating the need todewater, remove, stockpile, and eventually replace vast quantities ofearth to access the carrot. At conclusion of operations, tailings wouldrefill that smaller excavation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a close up of the pump and cutterhead assembly.

FIG. 2 is a representation of the dredge at the workface making a newcut.

FIG. 3 is a representation of the pump, cutter and traveler track,showing three hydraulic cylinders deployed from the dredge chassis (notshown) to crowd the pump, cutter, and traveler track into the work face.

FIG. 4 is a representation of a single large air supply linked toindividually valved buoyancy tanks on dredge and each section of dredgepipe to adjust individual buoyancies.

FIG. 5 is a representation of an embodiment that excavates in a curvedpath with pump, cutter and nearby structure supported by large drivenwheels riding on the excavation bottom.

FIG. 6 is a representation of an embodiment that excavates in a curvedpath with a curved track supporting wheels.

FIG. 7 is a representation of the curved track with rack and pinion totraverse the cutter and pump.

FIG. 8 is a representation of the curved track with endless cableway totraverse the cutter and pump.

FIG. 9 is three views representing a specialized pump that integratesthe closely coupled impeller and cutterhead.

REFERENCED DRAWING NUMBERS

-   1. A submersible dredge pump-   2. A submersible motor-   3. A cutterhead motor-   4. A motor driven cutterhead-   5. Two parallel trackways for traveler cars-   6. and 6 a traveler cars-   7. A connecting beam-   8. A spud, 8 a four additional spuds,    -   8 b two more spuds-   9. A rack and pinion-   10. A skid structures-   11. Three hydraulic cylinders-   12. An umbilical cable-   13. An electric branch line-   14. A second motor-   15. A large hydraulic pump-   16. Air control valve-   17. Attitude control tanks-   18. A dredge discharge pipe section-   19. A buoyant submerged dredge discharge    -   pipe-   20. A fixed discharge pipe-   21. Flexible ball joints-   22. Workface-   23. A long spar-   24. A large pointed plow-   25. Large wheels-   26. Drive motors-   27. Cables anchored right and left-   28. Winches-   29. Curved metal track-   30. Endless cableway-   31. A rack-   32. A pinion-   33. Traveler car-   34. Idlers-   35. Motor driven capstan-   36. Pump volute-   37. Pump discharge-   38. Integrated impeller and suction tube-   39. Cutterhead on suction tube-   40. Impeller vanes-   41. Impeller bearing-   42. Cutter bearing-   43. Planet gear-   44. Ring gear-   45. Drive motor-   46. ROV and its umbilical

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The configuration of the assembly of dredge pump, (1) detailed in FIG. 1driven for instance, by a direct coupled submersible electric motor, (2)and cutterhead (4) driven for instance, by a hydraulic motor (3).Cutterhead and pump are closely coupled to increase cutting power andpumping efficiency. A more remotely mounted pump has friction losses anda closely driven cutter has a greater mechanical advantage.

FIG. 2. A submerged hydraulic dredge comprising one track or twohorizontal parallel tracks (5) each carrying a traveler car. (6 and 6 a)One car mounts a submersible dredge pump, and dredge cutterhead driven,for instance by a hydraulic motor. (3 of FIG. 1) The movement of thetraveler cars is coordinated by a connecting beam. (7) The other car (6a) mounts a skid spud (8) that, with all other spuds withdrawn, can bedeployed into the bottom and traversed with the support of a traversingbottomed cutter to skid the chassis sideways. The traveler cars aretraversed synchronously by rack and pinion (9) incorporated in eachtraveler track or by, for instance, jackscrews or endless cablewaysincorporated in each traveler track. Four additional spuds (8 a) areattached, one onto either end of each track. Skid structures (10) arebuilt into either end of the chassis. Two additional spuds (8 b) aremounted in the skid structures to support corners of the remainingchassis. Not only can the dredge, skid itself right and left, it canalso move fore and aft by articulating the spuds and movable travelerbeam apart and together.

FIG. 3. The pump, cutter and traveler track standing apart from thedredge chassis, showing three hydraulic cylinders (11) deployed from thedredge chassis (not shown) to crowd the pump, cutter, and traveler trackinto the work face. Spuds on either end of the main traveler trackstabilize it after it is crowded forward so the cutter can energeticallyengage the workface. Electric power, control data and high pressure airis supplied from surface facilities by umbilical cable (12) attached tothe dredge convenient to the powered dredge pump. An electric branchline (13) leads to a second electric motor (14) powering a largehydraulic pump (15) mounted on the dredge. The hydraulic pump supplieshydraulic power to all spuds, various hydraulic cylinders and hydraulicmotors identified elsewhere.

FIG. 4. The air supply is distributed by a control valve (16) to supplyat least two variable buoyancy attitude control tanks (17) on the dredgetwo on each dredge discharge pipe section (18) and one tank on eachanchor (27 of FIG. 5). A free swimming ROV, its umbilical attached tothe dredge umbilical to supply power for motive thrusters, electroniccontrol data, and compressed air to provide lightening buoyancy and toreposition anchors and to perform other tasks on the bottom. Each suchcomponent must, on occasion, float to the surface for maintenance.Buoyancy tanks on the dredge can lighten the dredge to facilitate movingit about the bottom. Buoyant submerged dredge discharge pipes (19)transport, a slurry of water and excavated material from the dredge to afixed submerged discharge pipe (20) leading ashore. Buoyant pipesections analogous to float pipe on a surface dredge float a few feetabove the bottom of the excavation. As the percentage of solids in thedredge pipe increases, buoyancy must increase to keep pipes level andoff the bottom. The pipes are interconnected by flexible ball joints(21) that allow dredge and float pipe to articulate independently of thefixed discharge pipe going ashore. Control from the surface by means ofthe umbilical cable to the dredge relies primarily upon control datafrom real time under water imaging, for instance by side scan sonar, fordredge control about the bottom of the excavation.

DESCRIPTION OF OTHER EMBODIMENTS

The dredge of embodiment 1, but alternative to a chassis supported onspuds as in FIG. 2, and skidding the chassis with traversing mechanismsand by alternately withdrawing or extending spuds and spreading themwith hydraulic cylinders; the following variation is used:

FIG. 5. The cutterhead and pump are traversed in a curved path along theworkface (22) by attaching one end of a long spar (23) to the cutterheadand pump and attaching a large pointed plow (24) to the other end. Bothembodiments use the same submersible pump (1) and cutterhead (2),labeled in FIG. 1. The spar pivoting on the buried plow at one enddetermines an arc that establishes the curvature radius of the path ofthe cutter and pump at the other end. This embodiment carries the cutterend of the radius spar with large driven wheels (25), rolling in acurved path, on the bottom of the excavation driven by motors (26) tofacilitate swinging the cutter in an arc determined by the spar on itspivot. Cables anchored right and left (27) and spooled on winches (28)at the cutter end of the spar assist to swing the spar end right andleft.

FIG. 6. A slight variation of this embodiment places the wheelssupporting the spar on a curved metal track (29) resting on the bottomof the excavation and allows for the use of a rack and pinion or endlesscableway (30) on the curved track to traverse the cutter and spar.

FIG. 7 and FIG. 8. Shown are two representations of the curved metaltrack, FIG. 7 with a rack (31) and pinion (32) to traverse the carattached to the cutter and spar, FIG. 8 represents an endless cableway(30) running from traveler car (33) across idlers (34) around hydraulicmotor driven capstan (35) back across idlers to the cable car.

FIG. 9. A modification is made to a conventional dredge pump. Acutterhead is closely coupled with the pump as in other embodimentsherein and integrated with the pump impeller and rotates at pump speedas follows:

The pump volute (36) is made a relatively large diameter, leading to asingle pump discharge (37). The throat of the impeller is projected intoa suction tube integrating impeller and suction tube (38) incorporatinga cutterhead (39) at its end. The impeller is of a large diameter andbecause of impeller diameter; the impeller vane (40) tips turn at avelocity producing a pressure typical of all dredge pumps. At theimpeller mouth, close to the center of impeller rotation, the suctiontube and cutter turn at a much slower peripheral velocity typical ofdredge cutterheads. The rear impeller bearing (41) is confined withinthe volute and works with the cutter bearing (42) to keep the impellerand suction tube, turning true. The cutter bearing is supported (supportstructure not shown) for example, by structure leading from the pumpvolute or leading from the dredge chassis.

The impeller is driven by one or more planet friction wheels or gears(43) turning a ring or ring gear (44) attached to the face of theimpeller. The planet gears are driven by one or more electric orhydraulic drive motors (45).

1. A submerged remotely operated cutter head dredging system forexcavating a cut in a workface located at the bottom of a body of water,the system comprising: a chassis comprising a first track and a firstcar mounted on the track for movement along the track; a pump and cutterhead cutter head assembly mounted on the car for movement with the caralong the track, the pump and cutter head cutter head assemblycomprising (1) a dredging pump (2) a dredging cutter head and (3) meansfor driving the pump and the cutter head; means for propelling the caralong the track; means for effecting movement of the pump and cutterhead assembly into and away from the workface; a plurality of extendableand retractable spuds fastened to the chassis, the spuds beingextendable into a bottom surface of the body of water for supporting andstabilizing that chassis, and one or more buoyant submerged dischargepipes for transporting a slurry of water and material excavated by thepump and cutter head assembly, the buoyant discharge pipes being coupledto a fixed submerged discharge pipe leading to the surface of the bodyof water.
 2. The system as recited in claim 1, wherein the means foreffecting movement of the pump and cutter head assembly comprises two ormore parallel hydraulic cylinders carried by the chassis and orientedperpendicular to the track, the cylinders acting between the chassis andthe track carrying the pump and cutter assembly for forcing the car andthe pump and cutter head assembly toward the workface.
 3. The system asrecited in claim 2, and further comprising an additional retractable andextendable spud fixed to the track at each end of the track forstabilizing the track and the pump and cutter head assembly whileexcavating.
 4. The system as recited in claim 1, and further comprising:a second track parallel to the first track; a second car mounted on thesecond track and coupled to the first car by a beam and a hydrauliccylinder; an extendable and retractable spud fastened to the second car,whereby, with the spud on the second car extended into bottom surface ofthe body of water and all of the other spuds retracted, propulsionapplied to the first and second car car effects movement of the chassisalong the workface.
 5. The system as recited in claim 4, whereinmovement forcing of the pump and cutter head assembly and first trackinto the workface is effected by (1) selectively extending andretracting spuds on the first and second tracks and (2) actuating thehydraulic cylinders.
 6. The system as recited in claim 4, wherein one of(1) a rack and pinion, (2) a jackscrew and (3) an endless cableway isprovided in each track for propelling the cars along the first track toextend the cut made by the cutterhead.
 7. The system as recited in claim1, and further comprising a main umbilical conduit providing electricpower, control data, and compressed air from surface facilities forpowering motors in, and providing operational commands to, submergedcomponents of the system.
 8. The system as recited in claim 7, andfurther comprising: a main hydraulic pump mounted on the dredge andproviding hydraulic power to all spuds, hydraulic cylinders andhydraulic motors in submerged components of the system; and an electricbranch line leading to an electric motor driving the main hydraulicpump.
 9. The system as recited in claim 7, and further comprising: aplurality of anchors connected by cables to winches on the dredge; avariable buoyancy attitude control tank mounted to each anchor; aplurality of variable buoyancy attitude control tanks mounted on thechassis; a plurality of variable buoyancy attitude control tanks mountedon each of the discharge pipes; a conduit for pressurized airincorporated into the umbilical cable; and a master control valvecarried by the chassis and connected to the conduit for pressurized air,for supplying air for delivery to the control tanks.
 10. The system asrecited in claim 9, and further comprising: an ROV connected by anumbilical conduit to the main umbilical conduit and to the mastercontrol valve for (1) delivering electrical power and (2) deliveringpressurized air to the control tanks, for adjusting the buoyancy of thecontrol tanks, applying thrust to reposition anchors and performingother tasks about the bottom of the body of water.
 11. A submergedremotely operated cutter head dredging system for excavating a cut in aworkface located at the bottom of a body of water, the systemcomprising: a spar pivotally coupled at one end to a plow anchored inthe bottom of the body of water, the spar being supported at its otherend by a movable carriage, whereby the other end of the spar is movablealong a curved path determined by pivoting movement of the spar aboutthe plow; a pump and cutter head cutter head assembly mounted to theother end of the spar for movement with the other end of the spar andthe carriage along the workface, the pump and cutter head cutter headassembly comprising (1) a dredging pump (2) a dredging cutter head and(3) means for driving the pump and the cutter head; means for propellingthe carriage along the workface; and one or more buoyant submergeddischarge pipes for transporting a slurry of water and materialexcavated by the pump and cutter head assembly, the buoyant dischargepipes being coupled to a fixed submerged discharge pipe leading to thesurface of the body of water.
 12. The system as recited in claim 11,wherein the means for propelling the carriage comprises one of (1) arack and pinion and (2) an endless cableway provided adjacent to theother end of the spar.
 13. The system as recited in claim 11, whereinthe carriage comprises wheels mounted at the other end of the spar. 14.The system as recited in claim 12, wherein the carriage comprises wheelsmounted at the other end of the spar.
 15. The system as recited in claim11, and further comprising a main umbilical conduit providing electricpower, control data, and compressed air from surface facilities forpowering motors in, and providing operational commands to, submergedcomponents of the system.
 16. The system as recited in claim 15, andfurther comprising a plurality of variable buoyancy attitude controltanks mounted on each of the discharge pipes; a conduit for pressurizedair incorporated into the umbilical cable; and a master control valvecarried by the other end of the spar and connected to the conduit forpressurized air, for supplying air for delivery to the control tanks.17. The system as recited in claim 16, and further comprising: an ROVconnected by an umbilical conduit to the main umbilical conduit and tothe master control valve for (1) delivering electrical power and (2)delivering pressurized air to the control tanks, for adjusting thebuoyancy of the control tanks, applying thrust to reposition anchors andperforming other tasks about the bottom of the body of water.
 18. Thesystem as recited in claim 11, wherein the carriage is supported on andmovable along a curved track located adjacent to the other end of thespar.
 19. The system as recited in claim 18, wherein the means forpropelling the carriage comprises one of (1) a rack and pinion and (2)an endless cableway mounted onto the curved track.
 20. A pump and cutterhead assembly for use in a dredging system, the pump and cutter headassembly comprising: a pump incorporating (1) a large diameter voluteprovided with a discharge port and (2) a unitary assembly of a largediameter impeller and a suction tube rotatably mounted on the volute; aplurality of planetary driving devices mounted on the volute andengaging a periphery of the impeller for driving the impeller andsuction tube; and a dredging cutter head coupled to the impeller forreceiving driving force from the impeller.